Electropyrolysis apparatus



Dec. 2, 1958 Filed Dec. 16. 1953 E. STIRNE MANN EI'AL ELECTROPYROLYSIS APPARATUS 2 Sheets-Sheet 1 Inventors.- ERNST STIRHEI'IANH Arm mzaqofi EPHL AM?- Dec. 2; 1958 E. STIRNEMANN ETAL ,8

YELECTROPY'ROLYSIS APPARATUS Filed Dec. 16, 1953 2 Sheets-Sheet 2 In wen Z0219:

ERNST STIRNEMHHH AND THEoDoR Em/L I-Ar/z.

i d ta es P mi ELECTROPYROLYSIS APPARATUS Ernst Stirnemann, Basel, and Theodor Emil Lanz, Visp, Switzerland, assignors to Lonza Electric and Chemical Works Limited, Basel, Switzerland Application December 16, 1953, Serial No. 398,602

Claims priority, application Switzerland December 17, 1952 5 Claims. (Cl. 204-325) The present invention relates to an electropyrolysis method and apparatus. More particularly, the present invention relates to a method and apparatus for 'produc-' ing acetylene-containing gases from a liquid hydrocarbon such as oil which is decomposed by intermittent electric arc discharges produced between rotatable electrodes arranged in the liquid hydrocarbon. v

In prior known apparatus for the production of 'acetylene-containing gases by methods of the above type, several disadvantages are present, such as the necessity for carrying out the process with rather high voltages, so that electric arcs of relatively long duration are formed, which results in a poor power factor. In order to carry out the process of obtaining acetylene-containing gases by electrical arc discharges in an economical manner and with the production of a high proportion of acetylene, it is of great importance that the power factor (cos (p) be made as high as possible. A

It has now been found that the manufacture of acetylene or acetylene-containing gases from liquid hydrocarbons by means of intermittent arc discharges between rotatable electrodes arranged in the liquid hydrocarbon can be carried out at comparatively low voltages, as for example, at 50-500 volts. Such voltages, however, require a very small spacing between theelectrodes, which in apparatus heretofore known, could not be maintained constant during the continuous operation of the apparatus. This is even more so in view of the fact that the rotatable electrodes are not subjected to absolutely uniform wear.

It is an object, therefore, of the present invention to provide a method and apparatus for carrying out an electropyrolysis process of the above type which overcomes the above mentioned disadvantages.

.It is another object of the invention to provide a method and apparatus wherein the above mentioned electropyrolysis process may be carried out at a comparatively low voltage.

It is still another object of the invention to provide a method and apparatus, of the above type whereinv the necessary minimum spacing between the electrodes may be easily and automatically provided during the operation of the process.

With the above objects in view, the present invention concerns, in its broad aspects, a method of producing an acetylene-containing gas mixture from liquid hydrocarbons which comprises the steps of arranging at least two rotatable roller electrodes in a liquid hydrocarbon spaced from each other a predetermined distance, whereby at least one of these rotatable electrodes is mounted freely movable toward and away from the other electrode or electrodes, producing intermittent electric arc discharges between the electrodes while rotating the electrodes, and relatively moving the axles of the electrodes closer to each other as the electrodes become worn by the electric arc discharges for maintaining the electrodes spaced apart the predetermined distance.

I he invention also consists in an electropynolysis ap- 2,862,866 Patented Dec. 2, 1958 2 paratus which broadly comprises, in combination, a vessel for containing a liquid adapted to be electropyrolyzed by an electric discharge, at least two rotatable electrodes arranged inthe vessel spaced from each other a predetermined distance and adapted to extend into the liquid to electropyrolyze the same, at least one of the electrodes being mounted freely movable toward and away from the other electrode, and means for moving the one electrode toward the other electrode, whereby the electrodes may be relatively moved closer to each other as the electrodes become worn by electric arc discharges produced therebetween so as to maintain the electrodes spaced apart the predetermined distance.

In accordance with the invention, the freely movable electrode or electrodes are urged toward a stationary electrode or toward each other by means of forces present within the system. The relative movementof the electrodes toward one another can be produced by various means which operate on the freely moving electrodes, as for example, by springs or other resilient means, which may comprise rubber, air, and so on, by the operation of gravity, by hydraulic and pneumatic forces, by magnetic or electrical forces, or, for example, by the suction effect produced by the liquid hydrocarbon or oil film moving between the rotating electrodes, which may be of roller v form.

either or both may be mounted so that their spindles,

about which they rotate, are freely movable toward each other, or only one electrode may have its spindle thus freely mounted. The spindle of the stationary rotatable electrode can either be fixed permanently or may be adjustable. The spindles of the freely mounted rotatable electrodes may be mounted in slidebars or may be made movable by means of swing arms, as more fully described therein. At least one .of the electrodes, must be driven, but if desired several orall of the electrodes may be driven. Preferably the direction of turning of adjacent electrodes is opposite with respect to each other. By control and regulation of the speed of rotation of theelectrodes, of thetemperature of the liquid .to be electropyrolyzed, of the electrode moving means, suchcontrol being carried out individually or in combination, it is possible to obtain the optimum conditionsfor each type of hydrocarbon with respect to the current output.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood'from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

Fig. 1 is a side view of an apparatus constructed in accordance with the invention including two electrodes;

Fig. 2 is a side view showing an embodiment of the invention including three electrodes;

Fig. 3 is a perspective view of an apparatus similar to that shown in Fig. 1 showingthe means for mounting the'movable electrode and meansforrotating the electrodes;

Fig. 4 is a side view of an apparatusm accordance with the invention including fluid pressure means for.

moving the movable electrode; a 2

Fig. 5 is a side view of. another embodiment ofthe invention including spring means for moving themovable electrode; I

Fig. 6 is a side view of still another embodiment of the invention including electrical means for moving the movable electrode; and

Fig. 7 is a side view of still a further embodiment of the invention showing'an an'a'ngement whereinthe movable electrode is moved by gravity. 1

Referring now to the drawings, andlparticularly to Fig. 1, there is shown a vessel 20 which is of fluid-tight construction, the vessel being formed with an inlet 21 for introducing a liquid hydrocarbon 22 into the vessel and having an outlet 23 therefor. The liquid hydrocarbon 22. contained in vessel 20 is adapted to be electropyr'o'lyzed' and decomposed to produce ates/1e or acetylene-containinggases which are discharged through outlet 24 formed in vessel 20.

Mounted within vessel 20 and immersed within the liquid hydrocarbon is a stationary roller electrode 3, electrode 3' being 'inou n't'ed with its spindle 2 supported on a bracket 1. Bracket 11S mounted on the bottom of vessel 20 so as to be adjustable by means including. supporting base 25 which has plurality of apertures therein adapted to selectively receive the mounting bolts 2626 or the like provided at the bottom of the" legs of bracket 1. In this way, the stationary electrode 3 can be fixed in a selected position in the vessel 20i Extending above stationary electrode 3 and movable roller electrode 8 is a slide bar 4 on which a slid'able suspension sleeve 5 is mounted, sleeve 5 being adapted to be fixed in position at any desired point along slide bar 4. Pivotally connected at one end to the suspension sleeve 5 is a swing arm 6 which is connected at its other end to the spindle 7 of movable electrode 8, it being seen, as shown in Fig. 3, that preferably two swing arms 6 and 6 are provided for attachment to spindle 7 at opposite ends thereof.

Also, as more clearly shown in Fig. 3, the electrodes may be rotated by means of electric motors 2727'. As indicated by the arrows shown in Fig. 3, and as pointed out above, the directions of rotation of the, electrodes are preferably opposite to each other.

It will be apparent from the supporting arrangement shown in Figs. 1 and 3 that electrode 8 is constantly urged toward stationary electrode 3 by the swinging movernent afforded through its attachment to supporting slide bar 4 by means of swing arms 66?, the degree of force exerted on the movable electrode 8 in a direction toward the stationary electrode 3 being variable depending on the particular position at which suspension sleeve 5 is arranged on slide bar 4. The particular position along slide bar-4 at which sleeve 5 is fixed will be determined in part by such .factors as the speed of rotation of the electrodes and the viscosity and temperature of the hy-. drocarbon in which the electrodes are immersed.

Also shown in Fig. 1 is a form of electric circuit. which may be utilized in accordance with the invention, there being provided in this embodiment connecting lead 3 wires 9 attached to electrodes 3 and 8,.respectively, an electricity generating source 28, and a condenser 29.. Condenser 29 may be provided for the. purpose of'vary ing the phase displacement between the voltage and the current intensity in the use of alternating currentin the circuit. Instea'clof a condenser, asinduction coil Silas shown in the circuit illustrated in Fig. 2 may be used if desired. V

Fig. 2 shows an embodiment of. the invention, similar to that of Fig. 1 but omitting the showing of the hydro: a carbon containing vessel and the adjustable mountingfor' the stationary electrode illustrated in Fig. 1, wherein three rotatable electrodes areemployed instead of two as shown in Fig. 1, andwherein theswing arm support- 7 ing arrangement is locatedin a difierent position from that shown in Fig. 1. In this embodiment, the .supporting slide bar 14 is arranged below. the spindles, ofzthe rotatable'electrodes, and two of theel'ectrod'es 18 and 18'. are arranged on opposite sides of a central stationary electrode 13 and are freely movable by virtue of their mountings on swing arms 16 and 16', respectively, it being understood that the swing arm 16 is connected to a slidable sleeve member similar to sleeve 15 on slide bar 14. The swing arms may be provided in pairs similar to those shown in Fig. 3 for connection to the opposite ends of the spindles of the respective freely'movable electrodes. By virtue of the arrangement shown in Fig. 2,

electrodes 18 and 18 are constantly urged toward the central stationary electrode 13, and the degree of force with which they are urged toward the central electrode may be adjusted in a manner similar to that described with respect to the embodiment shown in Fig. 1.

In the Fig. 2 embodiment, an electric circuit is shown which includes conducting lead wires 19 connected respectively to the spindles 17,-1.2, and 17- of the respective rotatable electrodes, lead wires 19 being connected in circuit with'an electric generator 29' and an induction coil 30 which may be used for varying the phase shift of the electric current, as mentioned above. While support bracket 11 for electrode 13 is shown in a fixed stationary arrangement, it should be understood that means for adjusting the relative position of this supporting bracket may be provided, if desired, as shown in Fig. 1.

matic r'noving device.

\ piston 36, in the operation of the device, bears against spindle 31, the driven piston 36 being actuated by a driving piston 37 through a gaseous or a liquid medium arranged between the two pistons, the driving piston 36 being actuated by any desired and suitable means.

Fig. 5 shows still another embodiment of the invention wherein the spindle of the movable electrode 38, mounted similarly to that shown in Fig. 4, is constantly urged totrode with the desired force. Fig. 6 shows still another embodiment of the invention wherein the spindle of the movable electrode 40 maybe urged toward the stationary electrode by an electricallyactuated mechanism such as the solenoid 41 shown in' Fig. 6, the rod 42 connected to the core of the solenoid engaging the spindle of the movable electrode for urging it toward the stationary electrode when the solenoid 41 is energized.

Fig. 7 shows still a further form of the invention wherein the movable electrode 43 is arranged above the stationary electrode in a manner such that it moves constantly toward the stationary electrode. by the action of gravity, the suspension means'44 and 44' being of such type, as for example elastic members, that the force exerted by the weight of the movable electrode 43 may be controlled.

It should be understood that the specific embodiments described above and shown in the drawings are set forth only for the purposes of illustration, it being 'possible' to.

make various structural modifications without departing from the scope ofthe invention. For example, instead of providing separatemotors for rotating each of the electrodes as shown in Fig. 3, it may be suitable to use only a'single electric motor, and by'the use of a proper gearing mechanism the rotation of the electrodes maybe produced in opposite directions.

By virtue of the present invention, the electrode spacing and the particular film thickness of the hydrocarbon be tween the electrodes may be maintained completely automatically in order to provide for a low voltage, the proper 5. electrode spacing being carried out in spite of the operational wear of the electrodes by means of the above mentioned suction force of the hydrocarbon film, by spring action, or by the other devices described above and shown in the drawing.

Very great wear which results from the continuation of the processover a rather long period, e. g., several days, and which markedly changes theoperational conditions can be compensated for by manual adjustment'or automatically by means of suitable apparatus.

The rotatable electrodes maybe made of any suitable material, carbon electrodes being appropriate for use in the invention. Instead of such electrodes, other electrically conducting materials may be used which are capable of withstanding the electric arc temperatures, as, for example, graphite or silicon carbide.

Any liquid hydrocarbon may be used as the starting material for the production of acetylene or the production of acetylene-containing gas mixtures. Advantageously, inexpensive mineral oil may be used which distills at approximately l50-350 C.

The temperature of the liquid hydrocarbon in the reaction vessel depends upon the viscosity of the oil. In treating oil having a viscosity of, for example, 28 centipoise, at 50 C., temperatures of about 50100 C. have been found suitable. In carrying out the process in accordance with the invention, it is possible to work with not only a pair of electrodes, but it is also feasible to utilize, for example, three coacting rotatable electrodes, as shown, for example, in Fig. 3. Further, if elongated rotatable electrodes are used, these electrodes may be subdivided. It is also possible to use several groups of electrodes, as, for example, pairs of rollers which are electrically connected in series or in parallel.

The shape of the rotatable electrodes may be of different forms. The electrodes can be made disk-shaped by multiple subdivision thereof, but in general, roller-shaped or cylindrical electrodes are preferable. Instead of employing rotatable electrodes having a cylindrical peripheral surface, electrodes having a peripheral surface in the shape of a truncated cone may be used. It has been found that in using cylindrical or drum-shaped rotatable electrodes, it is of advantage to use such electrodes having a diameter of between and 60 centimeters, and preferably between 30-50 .cm. Experiment has shown that where the voltage supplied is in the range of 50-500 volts, preferably in the range of 60-150 volts, the current density is advantageously adjusted up to 10 amperes for each cm. of the length of the electrode cylinder. In the use of alternating current, as mentioned above, a suitable device may be used to change the phase displacement between the voltage and the currentintensity, as, for example, by using an induction coil or a condenser. The proper amount of such inductance or capacitance can be determined only by experiment, since they depend on the electrical characteristics of the apparatus, of the liquid hydrocarbon and of the voltage and current load. It has been found that for cylindrical electrodes of 8 cm. width and with a voltage supply of 100 volts, an inductance of 2-5 millihenrys is suitable.

The following examples are given for the purposes of illustration only, and are not to be understood as limiting the scope of the invention in any way.

Example I In carrying out the process in accordance with the invention, two rotatable roller electrodes are used, of which the spindle of one is mounted in afixed bearing and the other is mounted freely hung on a pendulum swing support. If the electrodes are immersed below the surface of an oil contained in a vessel and if rotated therein, the freely hanging roller electrode swings toward the stationary electrode, so that for a roller width of 4 cm. and at a peripheral speed of 10 meters per second at an oil viscosity of 10 centipoises, an opposing Constituent: Percent volume C H and homologues thereof 36.6

2 p I 57.7 G u, 3.8 CH 1.6 n 2n+2 0.6

In the electric circuit an inductance of about 3 millihenrys isprovided. The power factor amounts to 0.8 and at a load of 2 kw. there is produced an energy consumption of 4.5 kw. hours per standard cubic meter of gas mixture.

Example 11 V In an apparatus a pair of rotatable roller electrodes having a diameter of 30 cm. and an active roller width of 50 cm. are arranged in an oil bath, the electrodes being rotated at 600 revolutions per minute at a peripheral speed of 9.4 meters per second. One of the roller electrodes is mounted stationary while the other is mounted for free movement. The average current intensity amounts to 300 amperes and the voltage between the electrodes about volts. Under these conditions there is produced for each hour 6,000 standard liters of a gas mixture having a content of 36.6% volume of acetylene. The energy consumption is about 4.2 kw. hours per standard cubic meter of the gas mixture and the power factor amounts to about 0.85.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of electropyrolysis apparatus differing from the types described above.

While the invention has been illustrated and described as embodied in an apparatus for producing acetylene from liquid hydrocarbons, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended Within the meaning and range of equivalence of the following claims.

It should be understood that in the embodiments such as shown in Figs. 4-7 while the moving means is shown only at one end of the electrodes such moving means may be provided at both ends of the electrodes.

What is claimed as new and desired to be secured by Letters Patent is:

1. In an electropyrolysis apparatus, in combination, a vessel adapted to receive a liquid; at least two roller electrodes; means for connecting said electrodes to a source of electric current; and mounting means for rotatably mounting both of said electrodes on substantially parallel axes in said vessel and for also mounting at least one of said electrodes for free movement into peripheral contact with and away from the other of said electrodes, but continuously urged in direction toward said other electrode.

2. In an electropyrolysis apparatus, in combination, a vessel adapted to receive a liquid; at least two roller electrodes; means for connecting said electrodes to a source of electric current; mounting means for rotatably mounting both of said electrodes on substantially parallel axes in said vessel and for also mounting at least one of saidelectrodes for'free movementinto peripheral contact'wi'th and away from the' other of said electrodes, butcontinuously urged in direction-towardsaid'otlier electrode; and means for rotating at least one of said electrodesaboutits axis.

3. In an electropyrolysis apparatus, in combination; a vessel adapted to receive a liquid; at least;two roller electrodes; meansfor' connecting said electrodes to a source of electric current; mounting means for rotatably mounting both of said electrqdes on substantially parallel axes in said vessel andfor also mounting at least one of said electrodes for free movement into peripheral contact with and away from the other of said electrodes, but continuously urged in direction toward said other electrode; means operatively associated with said mounting means for adjusting the initial position which said electrodes occupy relative to each' other; and means for rotating at least one of said electrodes about its axis.

4. An electropyrolysis apparatus, comprising, in combination, a vessel adapted to receive a liquid; at least twotrolle'r electrodes; means for connecting said electrodes to a source of electric current; mounting means for rotatably mounting both of said electrodes on substantially parallel axes in said vessel and for also mounting at least one of said electrodes for free'movement into peripheral contact with and away from the other of said electrodes, but continuouslyurged in direction toward said other electrode; means for rotating said electrodes about theirrespective axes; and means for'producing an electric potential difference between said electrodes.

5. In an electropyrolysis apparatus, in combination, a vessel adapted to receive a liquid; at least two roller electrodes; means for connecting said electrodes to a source of electric current; and mounting means for rotatably mounting both of said electrodes in said vessel and for also mounting, at least one of said electrodes for free movement into peripheral contact with and away from the other of said electrodes, but continuously urged in direction toward said other electrode;

References Cited in the file of this patent UNITED STATES PATENTS 1,744,173 Longhi Jan. 21, 1930 1,887,658 Nutting Nov. 15, 1932 2,353,770 Suits July 18, 1944 2,632,731 Von Ediger Mar. 24, 1953 

1. IN AN ELECTROPYROLYSIS APPARATUS IN COMBINATION, A VESSEL ADAPTED TO RECIEVE A LIQID; AT LEAST TWO ROLLER ELECTRODES; MEANS FOR CONNECTING SAID ELECTRODES TO A SOURCE OF ELECTRIC CURRENT; AND MOUNTING MEANS FOR ROTATABLY MOUNTING BOTH OF SAID ELECTRODES ON SUBSTANTIALLY PARALLEL AXES IN SAID VESSEL AND FOR ALSO MOUNTING AT LEAST ONE OF SAID ELECTRODES FR FREE MOVEMENT INTO PERIPHERAL CONTACT WITH AND AWAY FROM THE OTHER OF SAID ELECTRODES, BUT CONTINUOUSLY URGED IN DIRECTION TOWARD SAID OTHER ELECTRODE. 